1. Field of the Invention
The present invention is in the field of vacuum-type circuit interrupters and is specifically concerned with the composition of the vapor condensing shield of the interrupter.
2. Description of the Prior Art
It is customary in vacuum-type circuit interrupters to provide a vapor condensing shield to prevent the outward dissemination of the arc and included metallic particles from damaging, or in the case of the metallic particles, from adhering to the outer insulating walls of the vacuum interrupter.
U.S. Pat. No. 4,020,304 entitled "Two-Material Vapor Shield for Vacuum-Type Circuit Interrupter" teaches a vacuum-type interrupter in which at least that part of the vapor condensing shield in the area of the arc consists of copper. The remainder of the shield may be copper or steel.
It is well known that the separable metallic electrical contacts may be constructed of a copper-chromium composition.